A mounted-board manufacturing system, which manufactures circuit boards on each of which components are mounted (hereinafter, referred to as “component mounted boards” or “mounted boards”), includes: a printer that prints solder paste on each circuit board; mounters that mounts components on the circuit board with printed solder paste; and a reflow machine that solders the mounted components.
Target circuit boards are transported on a line of a conveyer in the mounted-board manufacturing system and manufactured as mounted boards in the conveyer system. More specifically, respective machines perform their processes for each circuit board. For example, for each circuit board, the printer prints solder paste on the circuit board, the mounter mounts various-sized numerous components on the circuit board, and then the reflow machine solders the components. Each of mounted boards is manufactured in a series of manufacturing processes performed by these machines. Such a mounted board manufactured in the above-described manner is eventually embedded in an end product such as a home appliance.
This mounted-board manufacturing system sometimes produces defective component mounted boards. From among various causes of poor quality, there is a defect in printing solder paste. For example, if a defect occurs in printing solder paste on a circuit board but subsequent processes are performed on the printed board, in more details, components are mounted and soldered on the circuit board, this results in various wastes in use of the mounted-board manufacturing system, consumption of the components, and the like.
To reduce the number of defective products and reduce waste processes in the mounted-board manufacturing system, it is effective to detect occurrence of a defect in an early stage and take measures when the defect occurs in the middle of a series of the manufacturing processes.
Conventionally, a technique has been proposed by which an inspection machine arranged for a process subsequent to a printing process inspects how a printer prints solder paste on each circuit board (see, Patent literature (PTL) 1 for example). In the technique as described in PTL 1, position, area, and others of the printed solder paste are measured using two-dimensional image captured by a camera with a solid-state image sensing device. In addition, a height of printed solder paste is also measured using a laser ranging unit.
Based on the position, area, and height of the solder paste measured in such a manner, the inspection machine can inspect how the printer prints solder paste on each circuit board.